Niobium alloys



United States Patent 3,395,012 NIOBIUM ALLGYS George D. McAdam, Tamworth-in-Arden, and James S. Abercrornbie, Atherstone, England, assignors to The Birmingham Small Arms Company Limited, Birmingham, England, a British company No Drawing. Filed Nov. 8, 1965, Ser. No. 506,827 Claims priority, application Great Britain, Nov. 10, 1964, 45,767/64 14 Claims. (Cl. 75134) ABSTRACT OF THE DISCLOSURE A niobium-base alloy consisting essentially of to 25% tungsten, up to 40% tantalum, 0.1 to 10% of at least one element selected from the group consisting of ruthenium, osmium and iridium with the balance essentially niobium, said niobium being present in an amount of at least 30%.

This invention relates to niobium alloys containing tungsten as an essential element. It is particularly applicable to alloys containing some tantalum, although the inclusion of tantalum is not essential to this invention.

It has been found that the inclusion of platinum group metals of Group VIII of the Periodic Table has desirable effects on alloys including niobium and tungsten, with or without tantalum.

It is known that the addition of hafnium or zirconium and boron or carbon to niobium-tungsten alloys causes a strong precipitate after heat-treatment. It has now been found that the addition of platinum group metals to niobium-tungsten alloys including some hafnium or zirconium and boron or carbon further improves such alloys.

It is therefore an object of the present invention to improve the solid solution state strength of niobium-tungsten alloys, with or without tantalum, by the addition of platinum group metals of Group VIII of the Period Table.

It is a further object of the present invention to improve the strength of alloys containing niobium and tungsten with hafnium or zirconium and boron or carbon, with or Without tantalum, by the addition of platinum group metals of Group VIII of the Periodic Table.

According therefore to the present invention, there are provided alloys which consist by weight of at least 30% niobium and impurities, 10-25% tungsten, 0-40% tantalum, and 01-10% of one or more of ruthenium, osmium and iridium.

Preferred alloys include hafnium and/ or zirconium together with carbon and/ or boron in the following ranges:

Percent Hafnium 1.00-4.00 Zirconium 0.50-2.00 Carbon 0.05-0.20 Boron 0.05-0.20

The atomic ratio of hafnium and/or zirconium to carbon is preferably in the range 0.25-2.00 and the atomic ratio of hafnium and/ or zirconium to boron is preferably in the range 0.10-1.50.

Alloys according to the present invention may further include rh'enium 0.5-4% and/ or molybdenum 0.5-4%.

The examples listed in the tables below were prepared by conventional methods for this type of alloy, that is solution treatment of the alloy in the temperature range 3,395,012 Patented July 30, 1968 ice 1700" C.-2000 C., followed by ageing treatment in the temperature range 100 C.-1500 C. Alloys Numbers 1, 6, 9, 11, 13, and represent alloy compositions without the platinum group metals added.

The alloys listed in Table I were then tested to show the effects of platinum group metal additions to niobiumtungsten alloys, and niobium-tungsten-tantalum alloys on their solid solution strengths. The results of these tests are given in Table 2 below.

TABLE 2 Applied Secondary Hundred Alloy stress, Rupture creep rate, hour rup- Number tons/sq. in. life in percent per time stress, at 1,200 0. hours hour tons/sq. in. at 1,200 C.

TABLE 3 Composition (percentages by weight) Alloy Number Nb W Ta Zr Hf C B Ir Ru Os These examples Were first tested to show the favourable elfect of hafnium and/ or zirconium and carbon and/ or boron on niobium-tungsten and niobium-tungstentantalurn alloys. These results are given in Table 4, although this forms no part of the present invention.

TABLE 4 100 hr. rupture stress, tons/ Alloy number: sq. in. (1200 C.)

The effect of the addition of platinum group metals to precipitation-strengthened alloys is given below in Table 5.

TABLE 100 hr. rupture stress, tons/ Alloy number: sq. in. (1200 C.)

It is therefore clear that the addition of one or more of the platinum group metals osmium, iridium and ruthenium to niobium-tungsten and niobium-tungsten-tantalum alloys increases the solid solution strength of such alloys. It is also clear that such additions of platinum group metals also increases the strength of precipitationstrengthened niobium-tungsten alloys, with or Without tantalum.

We claim:

1. A niobium alloy consisting essentially of to tungsten, up to 40% tantalum, 0.1 to 10% of at least one element selected from the group consisting of ruthenium, osmium, and iridium, with the balance being essentially niobium, said niobium being present in an amount of at least 2. The niobium alloy of claim 1 further consisting essentially of 1 to 4% hafnium, and 0.05 to 0.2% of at least one element selected from the group consisting of carbon and boron.

3. The niobium alloy of claim 2 wherein the atomic ratio of hafnium to carbon is in the range from 0.25 to 2 and the atomic ratio of hafnium to boron is in the range from 0.1 to 1.5.

4. The niobium alloy of claim 1 further consisting essentially of 0.5 to 2% zirconium, and 0.05 to 0.2% of at least one element selected from the group consisting of carbon and boron.

5. The niobium alloy of claim 4 wherein the atomic ratio of zirconium to carbon is in the range from 0.25 to 2 and the atomic ratio of zirconium to boron is in the range from 0.1 to 1.5.

6. The niobium alloy of claim 1 further consisting essentially of 1 to 4% hafnium, 0.5 to 2% zirconium and 0.05 to 0.2% of at least one element selected from the group consisting of carbon and boron.

7. The niobium alloy of claim 6 wherein the atomic ratio of each of the elements hafnium and zirconium to carbon is in the range from 0.25 to 2 and the atomic ratio of each of the elements hafnium and zirconium to boron is in the range from 0.1 to 1.5.

8. A niobium alloy consisting essentially of 10 to 25% tungsten, up to 40% tantalum, 0.5 to 4% of at least one element selected from the group consisting of rhenium and molybdenum, 0.1 to 10% of at least one element selected from the group consisting of ruthenium, osmium, and iridium with the balance being essentially niobium, said niobium being present in an amount of at least 30%.

9. The niobium alloy of claim 8 further consisting essentially of l to 4% hafnium, and 0.05 to 0.2 of at least one element selected from the group consisting of carbon and boron.

10. The niobium alloy of claim 9 wherein the atomic ratio of hafnium to carbon is in the range from 0.25 to 2 and the atomic ratio of hafnium to boron is in the range from 0.1 to 1.5.

11. The niobium alloy of claim 8 further consisting essentially of 0.5 to 2% zirconium, and 0.05 to 0.2% of at least one element selected from the group consisting of carbon and boron.

12. The niobium alloy of claim 11 wherein the atomic ratio of zirconium to carbon is in the range from 0.25 to 2 and the atomic ratio of zirconium to boron is in the range from 0.1 to 1.5.

13. The niobium alloy of claim 8 further consisting essentially of 1 to 4% hafnium, 0.5 to 2% zirconium, and 0.05 to 0.2% of at least one element selected from the group consisting of carbon and boron.

14. The niobium alloy of claim 13 wherein the atomic ratio of each of the elements hafnium and zirconium to carbon is in the range from 0.25 to 2 and the atomic ratio of each of the elements hafnium and zirconium to boron is in the range from 0.1 to 1.5.

References Cited UNITED STATES PATENTS 3,115,407 12/1963 Hum et a1. 174 3,188,205 6/1965 Michael 75-174 3,230,119 l/l966 Gemmell et a1. 75-174 X 3,297,438 1/1967 Bradley et a]. 75174 OTHER REFERENCES AD 242 242, OTC PB 151091, DMIC Report 133, July 25, 1960, Tantalum and Tantalum Alloys, p. 110.

Zeitschrift fiir Metallkunde, vol. 54, No. 5, May 1963, pp. 317-319.

CHARLES N. LOVELL, Primary Examiner. 

